Various conditions can be treated with the application of light or optical energy of certain wavelengths. Many challenges exist in delivering the energy to the appropriate target structure (e.g., tissue such as the skin) without damaging tissue structures adjacent to the target structure. These challenges include delivery of energy at an appropriate wavelength with sufficient fluence, as well as the ability to effectively and efficiently scan the target structure with the light or optical energy.
Melasma is an example of one skin disorder of unknown etiology that causes a blotchy hyperpigmentation, often in the facial area. This condition is more common in women than in men. Although the specific cause(s) of melasma may not be well-understood, the pigmented appearance of melasma can be aggravated by certain conditions such as pregnancy, sun exposure, certain medications, such as, e.g., oral contraceptives, hormonal levels, genetics, etc. Exemplary symptoms of melasma include dark, irregularly-shaped patches or macules, which are commonly found on the upper cheek, nose, upper lip, and forehead. These patches often develop gradually over time. Melasma does not appear to cause any other symptoms, nor have other detrimental effects, beyond the cosmetic discoloration.
Unlike many pigmented structures that are typically present in the epidermal region of skin (i.e., at or near the tissue surface), dermal (or deep) melasma is often characterized by widespread presence of melanin and melanophages (including, e.g., excessively-pigmented cells) in portions or regions of the underlying dermis. Accordingly, treatment of dermal melasma (e.g., lightening of the appearance of darkened pigmented regions) can be particularly challenging because of the presence of the greater difficulty in accessing and affecting such pigmented cells and structures located deeper within the skin. Accordingly, conventional skin rejuvenation treatments such as facial peels (laser or chemical), dermabrasion, topical agents, and the like, which primarily affect the overlying epidermis, may not be effective in treating dermal melasma.